JP 3-50 National Search and Rescue Manual Vol I - US Navy

a. Wind direction and velocity.
b. Prevailing weather, such as rain, snow, or fog.
c. Wave height and direction.
d. Barometer readings.
e. Air and sea temperature.
f. Time of the observation.
g. Sudden weather changes, such as rapid clearing,
squall lines, changes in temperature, or cloud cover.
C. If communications are lost with the distressed craft, the SMC
should calculate the most probable position, using information gathered
to that point. If information is conflicting or sketchy, the SMC must
make assumptions about the craft's location. The accuracy of these
assumptions depends on the data collected and SMC ability to analyze the
information.
D. When evaluating reports of flare sightings, the SMC should
determine the location of the flare by carefully questioning the
informant and analyzing the data.
1. The location of each informant at the time of the sighting
should be plotted.
2. The characteristics of the flare, such as color, intensity,
duration, and trajectory should be obtained.
3. Preferably, cross bearings from more than one sighting should
be used for plotting the position of the flare. To obtain a
line of position (LOP) from an informant, the angle of the
sighting relative to a known bearing should be requested. If
the informant does not have a compass, the angle could be
determined by relation to a geographic feature such as the
shore line, a ridge line, or a straight road.
4. If only one sighting is available, obtain an LOP from the
informant as described in the previous paragraph and estimate
distance to the target. This estimate should be based on a
description of the flare, its observed height, the height of
the eye of the informant, and the visibility. If the
information is limited, determine the maximum distance the
flare could be seen and extend the search area appropriately.
5. Since the military is the major user of flares, an immediate
check of operating area events should be made following a
flare sighting.
E. Establishing overdue craft location is an elimination process.